is he cheating?

So my ex messaged me the other day and it was all innocent. but yesterday which I know I shouldn't have done I messaged him just seeing how he was doing. I was talking to this guy but I stopped talking to him he's getting really clingy so I told him that we couldn't do it anymore and just to be friends. well my ex asked how we were doing and I told him that I wasn't with him anymore and that he was too clingy. I asked him if he was talking to anyone just to see and he said that he was an even sent me a picture of a girl. so I said that's cool and asked him if he wanted me to let him go so he can talk to her and he said now she's asleep so we kept talking for just a little bit longer and out of the blue he said I'd still f*** the hell out of you. to be honest I was really surprised that he said that but I have missed him and that way and he keeps asking me when we can do it. I told him what about your girl and he said that they aren't official yet and I was like arent guys are going to make it official soon and he said no she's too good. So would it still be cheating if I did sleep with him even though they aren't official?